Been looking to try a new laptop; curious about the X 00/01 thinkpads.

Here's something I can think of:

1. Batteries. Both the inside and the bay one. A T400s might be better in this regard; but I assume it'll suffer the same issues.
2. Panels. I'll admit to being greedy by looking at this (https://i.imgur.com/8wPIsr9.jpg, X301 with a 14.1 panel) but other than the 1280x800 AFFS panel out there, I don't think there are any good panels. ("Good" means the IPS family and good brightness as well, perhaps Xiph could help with this.)
3. HDD/SSD. Those 1.8" are rather uncommon from what I hear.

Probably the best argument against is that it's not such a huge bump from my X61s. Still, anything I missed or should know about?

If you're looking for a nice thin'n'light classic Thinkpad that can handle modern tasks... you should skip T400s and T410s for having sucky screens and bad battery life too. You'll only get decent battery life starting with the T420s 6 cell + ultrabay, and then the T430s with all of Ivy Bridge's efficiency benefits, again 6 cell + ultrabay, the classic keyboard mod, and the IPS FHD mod.

If you care for the novelty, by all means pick up an X301, they're really cool especially the light up bits and A31 style volume buttons on the keyboard.

I tried making the same jump - from the x6xs to an x301. Other options I tried included: x62, x200, x200s, x201, x201s, x220, T420s.

The size and weight of the x301 is great. As is the construction. Keyboard has about the same spacing as the x61 - kb on my x301 is a bit too stiff for me. I don't have a battery. The huge problem I had with the machine was the low contrast TN screen. I am not sure if Xiph has leds for it - screen may be too thin, and even if he did it wouldn't help the contrast much. I didn't notice much, if any, performance boost between the SU9400 and the L7500.

The x200 with a P8600 or P8800 is worth considering.
The x220 with an IPS is another choice, if you can stand the screen format.
Still another option, would be keep the x61s but overhaul your software -- review the software you use and either find more effecient software or optimize the software you have.

I tried making the same jump - from the x6xs to an x301. Other options I tried included: x62, x200, x200s, x201, x201s, x220, T420s.

And how do you think about X62 as jump from X61?
Some other ThingPads to stand in line: T430u - ultrabook but with the chiclet keyboard (i don't know can it be cured with classic keyboard mod like on T430, T(W)530) and upcoming X210. Last week i have gotten my X210, have assembled it and have loved it. Fullsized keyboard with normal Esc and Del from X201 + WUXGA screen and last gen Core-i CPU.
Last couple of years X201 with IPS screen mod was my daly driver. And now i think i can move on further.

PS
I ABSOLUTELY LOVE 4:3 screens but fullsized keyboard on X2xx have take my heart hands;)

My computer work is on Linux doing low cpu-intensive tasks (command line, often on remote machines, coding and reading text on simple web pages). For these tasks there was no difference between the x61s and x62. No difference between the L2400 and the I5-5200u either (for those tasks).

The x62 has a huge performance boost over the x61 for video playback and rendering, and cpu-intensive computing.

When I need compute power, I turn on another machine and connect to it over ssh from my x60s.

For having an X61s, an X301, a T400s and a T420s, I can say the X301 is not my favorite. It has never been and that, since the beginning. But it was rather difficult to find where I live to want one for my collection. I used it with Windows 7, Windows 8.1 and Windows 10 and for light usage (mainly internet surfing, listening to music and watch movies), there's no particular problem. I love the screen (the resolution compared to the size), the keyboard, the weight and the thinness of the chassis (and its rigidity), but :

– battery life sucks (I've one hour with the wind in my back and the battery has circa 30 % wear) ;
– the U9400 doesn't really shine. I had at some time 8 GB of RAM but I went back to 4 GB as the CPU is not powerfull enough to handle well big applications or number of little ones. A waste of memory ;
– the original SSD was better than an hard disk, but well, not much better than today eMMC. I changed it with a Kingston KC380 If i remember well ;
– the palmrest is smooth comfortable but leaves print traces everywhere. I'm good for a cleaning of the chassis everytime I use the PC...

So it's nice because it's rare, mostly, and it's not a machine I will take with me if I go out, but :

– the X61s is lighter, the keyboard is even better, the battery is new (I get between 8 and 9 hours with WiFi off and with and heavily trimmed down Windows 7 by myself). I can just regret the resolution (a basic XGA). Plus this Thinkpad litterally rose from the deads... I bought it 40 € with every password possible (supervisor, HD and boot and software password also on the disk), the previous owner had swapped every key of the keyboard and broke the space one in the process. I managed to get rid of every password, I repaired the keyboard (I bought a new german one for 7 €). It gives me one of the cheapest laptop of my collection and its also one which is almost like new ;
– the T400s is also very nice, I love the aspect ratio, the resolution (1440x900) and the great contrast ratio, I've an ultrabay battery and an aftermarket primary battery which is in relatively good shape, so I can use the laptop for 4 or 5 hours, I definitely love the weight compared to the fact it's a 14.1" laptop (3.75 pounds with the two batteries charged, a little less when they are discharged ). The keyboard is excellent. And the CPU is just fine for what I'm doing (SP9400). This unit has the 8 GB which were initialy in the X301 and I can use them. And this laptop has a particular story too. A friend of mine brought it for 30 bucks totally naked and for pieces, it booted but stopped after 30 seconds or so. I bought it to him, I cleaned it totally (I replaced the thermal paste, which was dry like rocks) and I rebuilt it from scratch. Not a single failure since ! Probably the cheapest of my Thinkpads after the X61s. And I'm happy when I see the prices of the T400s here in France (it's pretty rare, even more than the X301, and it costs around 200 or 300 €). The single drawback is the absence of a rollcage in the lid ;
– the T420s is nice given the fact it has an mSATA drive coupled with a 500 GB hard drive. The i5-2520M and the 8 GB of RAM are really nice (the laptop runs Windows 8.1 , installed in true UEFI mode, heavily modified too). The autonomy is between 5 and 6 hours (I use the same Ultrabay battery I use in th T400s), but there are two big problems : the keyboard is the same as the T400s one, but not the same brand and its not as firm, I hate it, the space bar wobbles... And the biggest problem is the screen, and thus the format of the machine... 16/9 and 1600x900. The difference is not huge compared to the T400s, but I curse it everytime I use the T420s... I practically never go out with the T420s for those two reasons.

I will receive an X220 this week (2 units in fact :p), and I've wanted one for a long time. I will have the power of the T420s in the size of a machine between X61s and T400s while keeping the autonomy of the X61s and with a resolution between 1024x768 and 1440x900. It sounds good. And I cross my fingers to have an unit with a keyboard similar to my T400s or, even better, to my T410 – the firmest / most comfortable of my "recent" laptops' !

Like this guy I have experience or ownership of the x200/201 x300/301 t410s/420s.

Even in its heyday the x301 was a very expensive machine with questionable performance under Win7.

I feel that an x200 w/ a higher performance C2D like a P8000/9000 would probably show the 301 a thing or two.

The x301 is a model of external design so if you like that sort of thing and its cheap enough then go for it.

I actually used my x200 x300 t400s day to day as work machines granted I was never hugely far from a wall socket.

Typically I would be connected to the network remoting to something while I had another machine w/ a com1 port on a cisco etc.

These are usable machines given their limitations.

Running a Intel 5300 wireless they were decent as net terminals.

I feel that the SP9400/9500 in a 400s is problematic these days so I shudder to think what a U9400 or the SL1200 or whatever is in an X300 is like in 2018! I suspect a T61 w/ a modest cpu would show them a clean pair of heels and these are older.

Garbage screens (significantly worse than the average TN) + no docking support.

Battery life may be OK (since it's a ULV CPU) if you have the 6-cell + bay battery and both are in good shape, but with how old these machines are at this point, it's not easy to find batteries in good shape.